A RECORDING VACUUM THERMOBALANCE

A recording quartz spring balance is described, with which weight changes up to 1000 mg. can be followed linearly on a millivolt recorder for samples weighing up to 10 g. During the recording operation the sample may be under vacuum or pressure and may be heated or cooled. The maximum practical sensitivity is about 20 millivolts per milligram and the over-all error in reading the record is about 1 millivolt. The temperature coefficient of fused quartz springs is reported to be − (1.25 ± 0.02) × 10−4 per degree centigrade in the range 20° to 35 °C.The device could be readily adapted for heavier loads and greater weight changes by using less sensitive springs and could be used for measuring dimensional changes of solids with a maximum sensitivity of at least 2000 mv. per millimeter.

Download Full-text

Behavioural cycles during Pseudopregnancy in confined populations of domestic rabbits and their relation to the histology of the female reproductive tract

Australian Journal of Zoology ◽

10.1071/zo9660173 ◽

1966 ◽

Vol 14 (2) ◽

pp. 173 ◽

Cited By ~ 3

Author(s):

RL Hughes ◽

K Myers

Keyword(s):

Reproductive Tract ◽

Sexual Attraction ◽

Physiological Activity ◽

Adaptive Significance ◽

Female Reproductive Tract ◽

Corpora Lutea ◽

Weight Changes ◽

Dimensional Changes ◽

Detectable Difference ◽

Domestic Rabbits

Female domestic rabbits living with vasectomized males in large compounds (3/16 ac in area) exhibited periods of sexual attraction and mating, together with other behaviour such as aggression towards other females, digging, burrow interest, and nest building at intervals of about 6 days or multiples thereof. The behavioural cycles occurred during pseudopregnancy (of about 18 days) and were not a manifestation of an underlying inherent sequential cycle or a typical mammalian oestrous cycle. Behaviour with a strong sexual component culminating in mating and ovulation was observed at the beginning (or end) of each of 54 pseudopregnancies. Similar behaviour was also grouped about either the sixth or twelfth days of pseudopregnancy or both. This behaviour was extremely variable in both incidence and the number of components involved. Sexual components occurred less frequently and only once culminated in mating and ovulation. The behaviour observed on the sixth and twelfth days of pseudopregnancy was not reflected in measures of physiological activity such as numbers of graafian follicles, diameter of graafian follicles or corpora lutea, or weight changes in ovaries or uteri. The histology of the ovaries, uterus, and vagina and dimensional changes such as ovarian and uterine weights, number and diameter of graafian follicles, and diameter of sets of corpora lutea showed no detectable difference from those reported by other workers during pseudopregnancy for caged female rabbits isolated from males. The incidence of 6-day and 12-day behaviour was highest in the autumn-winter months when sub-optimal reproductiveconditions prevailed and lowest in spring-summer. Some possible causal mechanisms and the adaptive significance of the sixth-day and twelfth-day periods of sexual behaviour are discussed.

Download Full-text

Temperature coefficient of the silica spring balance and estimation of errors in gravimetric adsorption measurements

Review of Scientific Instruments ◽

10.1063/1.1136425 ◽

1981 ◽

Vol 52 (1) ◽

pp. 101-104 ◽

Cited By ~ 2

Author(s):

V. E. Berkheiser ◽

P. V. Rao ◽

W. G. Pothier

Keyword(s):

Temperature Coefficient ◽

Spring Balance ◽

Gravimetric Adsorption

Download Full-text

A TUBULAR CAPACITOR OF STABLE VALUE

Canadian Journal of Physics ◽

10.1139/p64-138 ◽

1964 ◽

Vol 42 (8) ◽

pp. 1508-1521 ◽

Cited By ~ 5

Author(s):

M. Kanno

Keyword(s):

Temperature Coefficient ◽

High Precision ◽

International Comparisons ◽

Free Fall ◽

Precision Measurements ◽

Mechanical Assembly ◽

Voltage Coefficient ◽

Fused Quartz ◽

Recent Developments ◽

Very High

Very high precision measurements of capacitance have been achieved by recent developments of transformer bridge techniques. Reference capacitors for use with these bridges must be very stable with time and temperature, as well as having other superior characteristics, all of which are very difficult to achieve with the usual mechanical assembly of conductors.This new capacitor uses fused quartz or pyrex glass tubing simply as a support for deposited metallic electrodes, and results in capacitance values of 1 pF which are stable to within one part per million (p.p.m.) for at least six months. They have a temperature coefficient of less than 3 p.p.m./°C, a voltage coefficient of less than 1 p.p.m. for applied voltages from 10 volts to 100 volts, and stability of 1 p.p.m. after free-fall drops from 10-cm heights.It is anticipated that a capacitor of this style will prove to be very useful as a transportable standard of capacitance, and could be used in international comparisons of capacitance values.

Download Full-text

Accurate measurement of the temperature coefficient of the ultrasonic velocity of fused quartz near room temperature

Review of Scientific Instruments ◽

10.1063/1.1139382 ◽

1987 ◽

Vol 58 (9) ◽

pp. 1758-1761 ◽

Cited By ~ 2

Author(s):

S. E. Chen ◽

Steven W. Meeks ◽

George C. Johnson ◽

Andrew C. Tam

Keyword(s):

Temperature Coefficient ◽

Ultrasonic Velocity ◽

Room Temperature ◽

Fused Quartz

Download Full-text

Investigating the Underlying Effect of Thermal Modification on Shrinkage Behavior of Bamboo Culm by Experimental and Numerical Methods

Materials ◽

10.3390/ma14040974 ◽

2021 ◽

Vol 14 (4) ◽

pp. 974

Author(s):

Raviduth Ramful ◽

Thefye P. M. Sunthar ◽

Wenliang Zhu ◽

Giuseppe Pezzotti

Keyword(s):

Numerical Methods ◽

Longitudinal Crack ◽

Bound Water ◽

Longitudinal Direction ◽

Linear Increase ◽

Weight Changes ◽

Weakly Bound ◽

Bamboo Culm ◽

Dimensional Changes ◽

Increasing Temperature

This study probes into the root cause of split in thermally modified bamboo culm by investigating the underlying effect of thermal contraction with respect to its orthotropic nature by experimental and numerical methods while concurrently monitoring the chemical variation of its structure by Fourier transformed infrared spectroscopy (FTIR). In first part of this study, a non-linear increase in dimensional and weight changes of small clear bamboo specimens were observed with increasing temperature. The dimensional changes in the radial and tangential directions significantly exceeded that in the longitudinal direction. From FTIR results, shrinkage effect between 150 °C to 200 °C was associated with weight loss engendered by reduction in weakly bound water and increase in desorption of water content while alteration of its mechanical properties was attributed to changes in cellulose, hemicellulose, and lignin. From results of finite element method (FEM), the graded variation in thermal expansion coefficient, which showed the formation of a narrowed region of strain concentration corresponding to longitudinal crack propagation, was associated with the inducement of internal forces, namely tensile and compressive forces, at specific regions along the culm length. The results of this study can be useful to achieve optimized durability in modified bamboo for construction.

Download Full-text

Criteria for the evaluation of low-temperature Scanning Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100145820 ◽

1986 ◽

Vol 44 ◽

pp. 902-903

Author(s):

Alan Beckett

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Low Temperature ◽

Conformational Changes ◽

Chemical Vapour ◽

List Type ◽

Dimensional Changes ◽

Critical Point Drying ◽

Temperature Scanning ◽

Scanning Electron

Low temperature scanning electron microscopy (LTSEM) has been evaluated with special reference to its application to the study of morphology and development in microorganisms. A number of criteria have been considered and have proved valuable in assessing the standard of results achieved. To further aid our understanding of these results, it has been necessary to compare those obtained by LTSEM with those from more conventional preparatory procedures such as 1) chemical fixation, dehydration and critical point-drying; 2) freeze-drying with or without chemical vapour fixation before hand.The criteria used for assessing LTSEM for the above purposes are as follows: 1)Specimen immobilization and stabilization2)General preservation of external morphology3)General preservation of internal morphology4)Exposure to solvents5)Overall dimensional changes6)Cell surface texture7)Differential conformational changes8)Etching frozen-hydrated material9)Beam damage10)Specimen resolution11)Specimen life

Download Full-text